Strip spring construction



May 13, 1958 Filed Jan. 31, 1957 K. PITTS ET AL.

STRIP SPRING CONSTRUCTION 2 Sheets-Sheet 1 8 4 F/ I l r,- 56 38 in i 42I I I I ,PM -40 I i 38 I b oisgji: i a I I I ll ltl I l I JIM l 5s I l if m HIM M E i: I o i: "-38 i l 5 p a: H I

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INVENTORS.

Ken/lard Pitts Elmer A. Her o'er THE IR A TTORNE Y5 y 1958 K. PlTTS ETAL 2,834,403

STRIP SPRING CONSTRUCTION Filed Jan. 31, 1957 2 Sheets-Sheet 2 so 10 T4bill!!!" INVENTORS. K'ehnard Pitts Elmer A. Herider HE /R ATTORNE Y5United States Patent 9 STRIP SPRING CONSTRUCTION Kennard Pitts, Detroit,and Elmer A. Herider, Dearborn Township, Wayne County, Mich., assignorsto Rockwell Spring and Axle C0., Coraopolis, Pa., :1 corporation ofPennsylvania Application January 31, 1957, Serial No. 637,456

6 Claims. (Cl. 155-179) This invention relates to strip springconstructions and cushion assemblies made therefrom, and moreparticularly, to a one-piece spring'element formed from a length ofsteel strip spring stock and being directly securable to a frame.

The strip spring stock is cut to length according to one embodiment ofthe spring element hereof and is bent at acute angles at two points toprovide a supported straight center section for engaging the load and apair of supporting sections at the opposite ends thereof for supportingthe loaded. center section. The noted embodiment is primarily adaptedfor back rest cushions whereas another embodiment herein disclosedconstitutes a seat cushion element which is bent at three points andrebent at one of those points to provide a load engaging center portionsupported at one end by a portion forming an oval with that end of thecenter portion and an offset attaching terminal extending from anopposite side of the center portion at the opposite end thereof. In bothembodiments the attachment of the supporting portions of the spring to aspring cushion frame is such that each portionnmay be quickly caught ona locator pin or grommet and effectively secured at this one point only,to the frameand' in a novel manner thereafter preventing a loose jointor dislodgement at that joint. In each embodiment the attaching pointsare closely spaced in a comparative sense to the available spring span,requiring the spring to be foreshortened between the ends therebyarching the center portion outwardly under prestress to provide adesired contour with its resulting comfort. The actual pin or grommetconnection provides convenient locators for the spring and thesupporting portions of the latter are pierced with openings whichreadily catch upon the pin iocators when they come into registry there:with.

Further features, objects and advantages willeither be specificallypointed out or become apparent when for a better understanding of theinvention reference is made to the following description taken inconjunction with the accompanying drawings which show a preferred embodiment hereof and in which:

Figure 1 is a broken elevational view of a seat assembly arranged withseat and back rest cushions embodying the present invention;

Figure 2 is a broken plan view of the seat cushion of Figure 1;

Figure 3 is a perspective View of the seat cushion strip element afterbeing bent to form;

Figure 4 is a perspectiveview of the element illustrated in Figure 3after one end is turned under and attached to the load engaging springelement; and- Figures 5 and 6 are sequential views in enlarged crosssection showing the attachment portion of one of the spring elementsbeing secured to a frame member.

In particular reference to Figure 1 of the drawings, a seat cushionframe 10 of generally rectangular construction is illustrated which isprincipally intended for vehicle seating assemblies, primarily the frontseat of the .JCC

vehicle. It will be understood that the relatively shallow cushionhereinafter described provided on this frame adapts it adequately foruse as the seat cushion in a rear seat and with minor modification foruse as a seat back rest. A standard 12 rigid at the bottom with the rearof the seat frame 10 carries a back rest mounting racket 14 at its upperend. A folding type back rest frame includes upper and lower crossmembers rigid with a vertical pair of spaced frame members 20 and 22which at their lower ends pivot on a hinge pin 24 carried by themounting bracket 14 to fold the back rest downa wardly in conventionalway. The pair of vertical frame members 20 and 22 carries a back restcushion 26 forming one of the split halves of a split type back restwhich is only partially shown. The cushion 26 typifies each half of theback rest, however, and in one physically constructed embodiment of theinvention, incorporate-d seven bands forming the row of strip springcushion elements 28, 30, etc., and each being generally 2" in width andmade from 0.025" thick blue temperedsteel strip spring stock. Theelement 28 which is typical of the elements in that row includes asupported portion 32. covered with the usual foam rubber padding andupholstery cloth to support the load of a seat occupants back and havinga pair of bends 34 formed at its opposite ends to provide supportingportions 36 which are punched and secured by rivet connections 38 attheir terminals to the respective upper and lower cross mem: bers 16 and18 in the back rest frame. While in manufacture the strip element 28 maybe arched to a desirable degree, the spring herein illustrated isretained in flat strip form and is thereafter bent only at the two bends34 providing a straight center section which forms the supported portion32 and the opposite end sections around the bends being substantiallystraight and disposed in acute angular relationship to thestraightcenter section. When the end sections are drawn together into a fore,shortened position to be secured to the-rivet connections 38, they archthe supported portion 32 of each element outwardly and stress allportions into a continuous arouate shape.

In Figures 1 and 2, the seat cushion frame 10 includes front and rearcross members 40,42; which are joined together at their midportions ifdesired, but which in any case rest at their outer ends upon and aresecurely joined to a pair of spaced side rail members 44 in the frame,The cross members 40 and 42 mutually carry a row46 of seat cushionspring elements which in one physically constructed embodiment. of theinvention were fifteen in number constituted by one-piece bands whichwere gen erally 2" in width and made from 0.025 thick blue tent; peredsteel strip spring stock. Each of the spring ele; ments in the row 46includesa supported portion 48 adapted to be covered with the usual foamrubber and upholstery cloth to form a full width seat-cushion 50 andhaving first and second main bends 52 and 54 lengthwise thereof at oneend enabling the band to loop on itselfand carry a rivet 56 at theupperportion to form a closed oval 58. The upper structure of the closedoval. 58, therefore, constitutes a supporting portion at the intermediate location of the rivet 56 between the ends, of the supportedportion 48 and at-a lower. point the oval has rivet connections 38 ofthe character already noted which with similar connections is disposedin a row for securing the cushion elements at spaced'points to the frontcross member 40. A single rivet connection38, is usually suflicient forsecuring one spring element to the member 40 although two connections 38may be provided according to Figure 2 for each of the elements. seen atthe end ofthe row 46. l

At the opposite end of the spring element, the supported portion 48 iscrimped to form an upwardly offset attachment terminal 60 which liesfiat against the sloping upper wall of the cross member 42 and issecured thereto by means of another of the rivet connections 38 alreadynoted. The rivet connections on the rear cross member 42 are disposed ina row at spaced points therealong and one such connection is sufiicientfor each element in the row of strips 46 although two may be providedfor the end elements as indicated in Figure 2.

The construction of the seat cushion elements from a one-piece band ofspring strip stock is illustrated in Figures 3 and 4. While the bandduring manufacture may be arched to a desirable degree, the seat cushionspring element herein illustrated is retained in fiat form and isthereafter bent to form in a general P-shape by being crimped adjacentthe straight section at one end forming the attachment terminal 60 andby being bent at the opposite end so that adjacent the first main bend52 it has a straight section extending at an acute angle and from whicha straight extremity section 62 extends at a slightly oblique anglearound the second main bend 54. The extending section has a fasteneropening 64 punched therein midway of the bends 52, 54 and its straightextremity section 62 is punched with a fastener opening 66 adjacent theterminal. The straight center section of the element which forms thesupported portion 48 is punched with another fastener opening 68substantially transversely aligned with the fastener opening 64therebelow and the attaching terminal 60 is formed with another fasteneropening 70, all of which openings are preferably made by a punchingoperation prior to the bending and crimping operations. The crimpingoperation results in an S-shaped construction adjacent the attachmentterminal 60 providing a deep bend 72 with a relatively long angular arewhich is sufficient to give the required upward offset to the attachmentterminal 60 and further providing a rebend 74 immediately contiguous tothe deep bend for directing the terminal 60 to lie flat against thesloping wall of the associated transversely extending cross member 42.

The terminal of the extremity section 62 is turned under in the mannerof a spiral from its backwardly extending relaxed condition of Figure 3and forced into tangentially overlapping relationship with the supportedportion 48 whereupon the rivet 56 is fastened in the registeringfastener openings 66 and 68. The forward part of the supported portion48 thus arches outwardly stressing the closed oval 58 into acontinuously arcuate shape.

In Figures 5 and 6, the present rivet connections 38 are so made toavoid the need for providing actual separate rivet elements. Thespecific connection between the attachment terminal 60 of the stripelement and the frame member 42 is illustrated as typical of theconnections 38 used for attaching the various cushion element portionsto their associated cushion frame members. The frame members 40 and 42are metal, preferably steel, and a hollow grommet 76 is pierced andextruded outwardly of the frame member for a short length. This lengthis preferably suflicient to produce an upstanding guide pin effect forpiloting the fastener opening 70 as it is brought into a confrontingposition where it catches over and settles downwardly upon the grommet76. These grommets 76 in one design of the invention were in rows on thevarious frame members 16, 18, 40, and 42 and spaced approximately 3 /2on center. The ends of the supported portion 48 of the seat cushionelement must be slightly foreshortened in order for the opening 76 tocatch onto the grommet 76 and accordingly the supported portion 48assumes the dotted line arched position shown by the dotted lines 48a inFigure 5. Thereafter a spinning tool, not shown, is brought up to themouth of the hollow grommet 76 at its outer end and is rotated underpower in a conventional way thereby expanding the mouth of the openingand securely spinning down the metal of the grommet 76 about the mouthof the fastener opening 70. Inasmuch as there are no fasteners to handleor to sepa- 4 rately support in the fastener openings, the assemblerfinds it an easy matter with one hand to steady the spring element onthe grommet which thus provides a solid locator therefor and he then hasthe other hand free to handle and operate the spinning tool, not shown.

The foregoing strip spring elements 28, 30, etc., in one row in the backrest and the seat cushion elements in the other row 46 provide a desiredcontour for the cushions 26 and S0. The back rest springs 28 and 30 lendthemselves to various adjustments for changing the contour and forchanging the support which they apply to a load by changes of thepreformed angularity in the bends 34. By changing the gauge of the steelstrip stock thickness, the degree of hardness or softness of theseelements may be further controlled. The seat cushion elements in the row46 lend themselves to various adjustments for changing the contour andthe rate of deflection by changing the radii of the S-shaped bends andrebends 72 and 74 which are crimped together and also by changing theirdepth. Through changing the angular relationships of the bends and theirradii at 52 and 54 in Figure 3, further changes in contour and rate ofdeflection are obtained. It is highly important that the cross members16 and 18 and the cross members 40 and 42, respectively, be sufiicientlyclosely spaced that the transverse supporting surfaces which theypresent fall short of the attachment portions of the extended lengths ofthe spring elements. Thus the supported portions of the spring elementsmust be efiectively shortened to locate them on the grommets forsecuring them to the cross members thereby arching the supported portionoutwardly to the desired contour.

Variations within the spirit and scope of the invention described areequally comprehended by the foregoing description.

We claim:

1. In combination, a spring element made from a onepiece spring metalband having a supported portion and a pair of portions at the endsprojecting outwardly from opposite sides, one of which projectingportions extends at an acute angle from the supported portion and fromwhich a section is bent and overlapped in a joint to the supportedportion between its ends thereby arching a section of said supportedportion and stressing said extending portion into complementary archedshape, the other projecting portion of said pair having a substantiallystraight terminal joined to said supported portion by a main bend toproduce an upward offset between the two portions and further joined bya rebend for directing the terminal of the projecting portion for lyingflat against a transverse supporting surface, and spaced transverseframe members presenting integral spring securing means on which to pinrespectively said upwardly offset terminal and said extending portion ata point in the lower arch thereof opposite to the overlapped joint.

2. For use in cushion constructions, a one-piece spring element made ofa length of spring metal band having a supported portion and a pair ofportions at the ends projecting outwardly from oposite sides, one ofwhich projecting portions of said pair extends at an acute angle fromthe supported portion and from which a section is bent and overlapped ina joint to the supported portion between its ends thereby arching asection of said supported portion and stressing said extending portioninto an arcuate shape, the other projecting portion of said pair havinga substantially straight terminal joined to said supported portion by amain bend to produce an upward offset between the two portions andfurther joined by a rebend for directing the terminal of the projectingportion for lying flat against a transverse supporting surface, andopenings for mounting-fasteners formed in said upwardly offset terminaland in said extending portion at a point in the lower arch opposite tothe overlapped joint.

3. In combination, a strip spring element made from a one-piece springsteel band bent lengthwise at longitudinally spaced points into agenerally P-shape in relaxed state, each of the sections of the springelement joined by the bends being substantially straight and containinga fastener opening punched;' through that straight section of the band,means lodged in the appropriate associated fastener openings to rivet anend section of the strip element to another section thereof intangentially overlapped relationship to form a closed figure therewithstressed into an entirely arcuate, oval shape, a metal frame to supportthe spring element including a transverse supporting member below theopposite straight end section thereof, and spring securing meansincluding an upset grommet portion extruded from the metal of saidtransverse frame member to project through the fastener opening in thelast named straight end section and having the grommet metal spun overaround the mouth of said opening.

4. In combination with a plurality of spring cushion elements, atransverse support member of metal, said cushion elements each having asupported portion and supporting portions therefor including one portionextending at an angle from one end thereof from which a section is bentand tangentially overlapped in a joint to the supported portion betweenits ends thereby stressing said extending portion into a continuouslyarcuate shape, said supportingportions having fastener openings therein,and spring securing means comprising a row of spaced grommets adaptedfor spinning and being extruded outwardly from the metal of said memberto enter the fastener openings as locators when the supporting portionsof said spring elements catch thereupon for support.

5. A spring cushion construction for seats including a spring elementmade from a one-piece spring metal band having a supported portion and apair of portions at the ends projecting outwardly from opposite sides,one of which projecting portions extending straight from the supportedportion in acute angular relationship thereto, the end of said straightextending portion being bent backward under the supported portion toform an angle with said straight extending portion, a rivet for securingthe end of said last bent portion to the supported portion medially ofits ends and arching the included end of the supported portion therewithinto an oval shape, the other projecting portion of said pair having anattachment terminal joined to said supported portion by a main bend toproduce an upward offset between the two portions and further joined bya rebend for directing the attachment terminal flatly against atransverse supporting surface, and spaced transverse frame memberspresenting integral spring securing means on which to pin said springelement at points respectively on said upwardly offset attachmentterminal and on said extending portion.

6. A spring cushion construction for seats including a plurality ofspring elements each made from a one-piece spring metal band and havinga supported portion and a pair of portions at the ends projectingoutwardly from the opposite sides, one of which projecting portionsextending straight from the supported portion in acute angularrelationship thereto, the end of said straight extending portion beingbent backward under the supported portion to form an angle with saidstraight extending portion, a rivet for securing the end of said lastbent portion to the supported portion medially of its ends and archingthe included end of the supported portion therewith into an oval shape,the other projecting portion of said pair having an attachment terminaljoined to said supported portion by a main bend to produce an upwardoffset between the two portions and further joined by a rebend fordirecting the attachment terminal flatly against a transverse supportingsurface, and spaced transverse frame members presenting integral springsecuring means extruded outwardly from the metal thereof and spun overwithin fastener openings respectively provided in said upwardly offsetattachment terminals :and said extending portions of said springelements.

References vCited in the file of this patent UNITED STATES PATENTS132,350 Briggs Oct. 22, 1872 FOREIGN PATENTS 330,729 France -Q. July 7,1903 667,407 France June 17, 1929

